Conventionally, in a permanent magnet type magnetic field generator for MRI, permanent magnets which constitute a permanent magnet group are bonded to adjacent permanent magnets, a plate yoke or both of these, with adhesive.
However, such a construction may not be able to hold the permanent magnets which constitute the permanent magnet group sufficiently when the permanent magnet group is subjected to a mechanical load exceeding a normal design value due to vibration, impact, etc. during transportation of the magnetic field generator, and therefore can allow the permanent magnets to be separated from the adjacent permanent magnets or the plate yoke, or to detach from the permanent magnet group. In this case, it becomes impossible to keep magnetic field uniformity in the magnetic field generator for MRI, resulting in decreased magnetic field intensity.
Thus, proposals have been made for techniques of providing a formed material on a side surface of the permanent magnet group (See Patent Document 1 for example).
Also, proposals are made for techniques of using a magnet cover which protects the permanent magnet group (See Patent Document 2 for example).
Patent Document 1: JP Patent No. 2699250
Patent Document 2: JP-A 11-178808